Problem: Simplify the following expression: $n = \dfrac{k}{10} - \dfrac{k}{6}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10$ and $6$ $\lcm(10, 6) = 30$ $ n = \dfrac{3}{3} \cdot \dfrac{k}{10} - \dfrac{5}{5} \cdot \dfrac{k}{6} $ $n = \dfrac{3k}{30} - \dfrac{5k}{30}$ $n = \dfrac{3k -5k}{30}$ $n = \dfrac{-2k}{30}$ Simplify the expression by dividing the numerator and denominator by 2: $n = \dfrac{-k}{15}$